Indeed, that is my experience as well. Its mostly show and tell from people new to the hobbies who are in the growing phase. There is also a lot of trend chasing to be "in". I've seen this in all sorts of hobby sub.
I tried looking around for a decent motorcycle sub, you're right that one lacks some alternatives. For gardening, maybe try more specific subs like for your local area or a specific kind of gardening, flowers or vegetables or whatever, just something more specific and niche than just gardening.
For welding again, similar idea, look for more specific less general welding related topics that may have subs devoted to them.
It may not work for all topics but generally i've found, the more specific and niche you get, the. better chance you'll find something decent.
It's still just a chance, you may or may not be able to find what you're looking for, but this is generally what i've found.
• https://www.reddit.com/r/origami/
• https://www.reddit.com/r/PixelArt/
• https://www.reddit.com/r/Watercolor/
• https://www.reddit.com/r/MSpaintLikeBobRoss/
DIY hobbies also spawn good subreddits. See e.g.
• https://www.reddit.com/r/homelab/
And of course, there's the great and under-explored genre of "hobby X but for old people who aren't interested in the fads of hobby X" subreddits, e.g.
I water color paint, in the end I was pretty disappointed with it. I was hoping their might be helpful community but it's non existent
Additionally I have found virtually all hobby subreddits are dominated by newbies to the hobby. This is especially pronounced on /r/motorcycles but appears to be general. Hobby subs are places where newbies hear newbies give advice and then pass that advice on to other newbies as if they were experienced.
I keep seeing people say that niche hobby subs still have worthwhile discussions but I have yet to actually see this.